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中考命题者常常在试题中巧妙而隐蔽地设置一些“陷阱”.以考查同学们思维的敏捷性和严密性.现归类分析如下:1.隐含于物质性质中例1等质量的下列物质中,加入足量的稀硫酸充分反应后,生成二氧化碳最少的是().A.MgCO3(块状)B.CaCO3(块状)C.Na2CO3(粉末)D.NaHCO3(粉末)解析:块状CaCO3与稀硫酸反应生成微溶于水的CaSO4,附着在CaCO3的表面,CaCO3与稀硫酸不能继续反应,导致产生较少的CO2,答案为B.
The proposition test subjects often set up some “traps” in the test questions ingeniously and covertly to examine the agility and rigor of the students’ thinking. The classification analysis is as follows: 1. Implicit in the nature of the material in example 1 quality Among the following substances, after adding sufficient amount of dilute sulfuric acid to fully react, the least carbon dioxide generated is (). A.MgCO3 (block) B.CaCO3 (block) C.Na2CO3 (powder) D.NaHCO3 (powder) Analysis: The bulk CaCO3 reacts with dilute sulfuric acid to form CaSO4 that is slightly soluble in water and adheres to the surface of CaCO3. CaCO3 cannot react with dilute sulfuric acid, resulting in less CO2, and the answer is B.